Species of the week: Cane toad

The cane toad (Bufo marinus or Rhinella marina) is a large toad native to south and central America, which has had some pretty bad press. Its attempted use in pest control has led to populations being established around the world, often with serious consequences for native wildlife.

It is also known as the giant toad, for good reason: the average length is 10-15cm, but the largest ever recorded was a pet at 38cm weighing 2.65kg!

Adults are entirely terrestrial and breed in freshwater. They live in open grasslands and woodland, especially in human habitats such as gardens and ditches. Its diet includes small rodents, reptiles, amphibians and invertebrates. Unusually amongst frogs and toads, it eats dead matter as well as living matter, even household waste.

Females can lay thousands of eggs in strings of up to 20m long! Tadpoles typically hatch after 48 hours and are highly toxic to most animals. The toads also have an impressive tolerance to water loss, and one study demonstrated some can survive loss of over half their body water.

Its appetite and breeding success has led to its use as agricultural pest control; it even gets its name from its use against the cane beetle, a pest of sugar cane.

However, it poses a threat to native species which eat it, because the adults have poisonous skin and glands which secrete a deadly toxin. Introduced populations include Australia, Florida, the Philippines, and most of the Caribbean Islands. In Australia, a crocodile species and multiple species of lizards and snakes have declined in connection with cane toad introductions. The density of toads in Australia can be up to 100 times that in its native range.

Humans, however, make use of the toxin. For those inclined to lick the toad’s skin, it can produce hallucinations and in Australia it is a class 1 drug. Toxin from its glands is used as an arrow poison in its native range and for slowing the heart rates of cardiac patients in China.

It is easy to associate cane toads only with damages to native wildlife in Australia, but the characteristics which have caused it to become such a problem – survival, reproduction, poison – perhaps mean we should see it as a superpowered species in its native range.